<head>
    <meta charset="UTF-8">
    <style>
        .outerDiv {
            width: 500px;
            height: 300px;
            border: 1px solid green;
            background-color: rgb(230, 224, 224);
        }

        .innerDiv {
            width: 100px;
            height: 100px;
            border: 1px solid blue;
            /* float: left; */
        }

        .d1 {
            background-color: greenyellow;
            /*  float: right; */
            float: left;
        }

        .d2 {
            background-color: rgb(79, 230, 124);
            float: right;
        }

        .d3 {
            background-color: rgb(26, 165, 208);
            float: right;
        }
    </style>
</head>

<body>
    <div class="outerDiv">
        <div class="innerDiv d1">框1</div>
        <div class="innerDiv d2">框2</div>
        <div class="innerDiv d3">框3</div>
    </div>
</body>